Which one of the following ionic speeies has the greatest protonaffinity toi form stable compound ?

Options

A. `I^(-)`
B. `HS^(-)`
C. `NH_(2)^(-)`
D. `F^(-)`

Explanation

The corresponding conjugate acids are `HIgtHFgtH_(2)SgtNH_(3)`
Thus, the basic strength of the conjugate bases will be
`I^(-) lt F^(-) lt S^(2-) lt NH_(2)^(-)`
`NH_(2)^(-)`, the strongest conjugate base, has the greatest proton affinity to form stable compound `NH_(3)`.